Completely Unable to connect to a friend.

[A Former User]

I have followed all of the guides, looked at everything, and it simply doesn't work. I'm trying to play a game of custom zombies with a friend, and I follow the guide perfectly from my understanding. I load into the match, and my friend double clicks my name in the friends list, and nothing happens. UpnUp is enabled, or whatever the hell it's called. I tried having him connect with the console command, I tried connecting to him with both options, but nothing works.